Sleep-Deprived Men See Sexual Attraction That’s Not Really There

Lack of sleep causes people to see things that aren't there, and some tired men see sexually interested women.

Sleep-deprived men might think uninterested women actually want to have sex with them, research from the American Academy of Sleep Medicine suggests. Though the data is limited in scope, with plenty of caveats, it complements prior studies that have shown that sleep deprivation can impair judgement, and that exhaustion may affect men differently than it affects women.

Perhaps that’s why dads keep weirding out baristas. “Sleep deprivation could have unexpected effects on perceptual experiences related to mating and dating,” study coauthor Jennifer Peszka, associate professor of psychology at Hendrix College, said in a statement. “That could lead people to engage in sexual decisions that they might otherwise not when they are well-rested.”

Peszka’s research is built on prior work that has highlighted how lack of sleep dulls men’s abilities to make moral judgements. Some studies have found that , after more than 24 hours without sleep, a man’s prefrontal cortex (part of the brain responsible for decision-making) essentially shuts down. Men take more risks when sleep deprived, and there’s even evidence that sleep deprivation impairs cognitive processes in a way that’s comparable to being drunk. In other words, men wearing beer goggles may be as prone to misguided flirtation as men wearing sleep masks.

For this new study, Peszka surveyed a small sample of 60 college students after one night of sleep deprivation. Participants were asked to rate the sexual interest, sexual intent, commitment interest, and commitment aversion of different men and women. Before the experiment, both men and women assumed the women they were shown were nominally interested in sex. But after one night of sleep deprivation, men rated women’s sexual interest and and sexual intent as significantly higher. Sleep-deprived women, on the other hand, were immune to this misguided assessment.

“Poor decision-making in these areas can lead to problems such as sexual harassment, unplanned pregnancy, sexually transmitted diseases, and relationship conflicts,” Peszka says. “Which are all factors that have serious medical, educational and economic implications for both the individual and for society.”

Still, that’s an alarmist conclusion to draw based on only 60 participants (of whom 31 were single, college-aged men). Besides, there’s no evidence that the men surveyed would act on their sexual interpretations. Although Peszka and her coauthor did not respond to inquiries from Fatherly about the caveats, Noah S. Siegel, a physician and sleep specialist at Harvard Medical School (who was not involved in the study) confirmed that sleep deprivation could potentially take a disproportionate toll on men.

“There are circadian fluctuations in sex hormones, testosterone in particular, that could theoretically result in a difference between men and women,” Siegel told Fatherly. But, without more thorough research to confirm this, this contention remains theoretical. Until there’s more data, err on the side of caution and assume you need to go to bed—just not in the way you thought.